Peemoeller and Stevens: Age, size, and sexual maturity of Busycotypus canalicu/atus in Buzzards Bay, Massachusetts 
273 
The average proportion of mature 
channeled whelk in each interval (10 
mm SL or 5 mm LW) were plotted along 
with the fitted logistic maturity curves 
from the GLM for each sex in Figures 
6A and 6B, respectively. Estimated male 
SM50 was 115.5 mm SL (SE 2.2), and 
61.3 mm LW (SE 0.9) (Table 6; Fig. 6, 
A and B). Estimated female SM50 was 
155.3 mm SL (SE 3.0) and 80.6 mm LW 
(SE 1.9) (Table 6; Fig. 6, A and B). Es- 
timated male and female age at SM50 
was 6.9 years (SE 0.2) and 8.6 years 
(SE 0.3), respectively (Table 6). Conver- 
sion of LW to SW through regression 
yielded an SM50 of 66.0 mm SW (SE 
2.9) and 89.7 mm SW (SE 2.9) for males 
and females, respectively (Table 3). The 
SW regression was not sex specific. The current mini- 
mum size limit (69.9 mm SW) was equivalent to a size 
of 65.1 mm LW (SE 2.3) (Table 3). From the von Ber- 
talanffy growth model, age at minimum size limit was 
calculated as 7.5 years (7. 0-7. 9 years) and 6.3 years 
(6. 1-6.6 years) for males 
and females, respectively 
(Table 5). 
Discussion 
Table 5 
Estimates for the parameters of shell length (SL) or lip width (LW) for 
male and female channeled whelk (Busycotypus canaliculatus) from the 
von Bertalanffy growth model used in our study of this species in Buz- 
zards Bay, Massachusetts, in August 2010 and July 2011. Each estimate 
is given as value ±1 standard error (SE). L ln f=theoretical maximum SL; 
/f=growth coefficient; ^theoretical age at length 0. 
Sample 
Model 
size (n) 
T-inf 
K 
to 
Female SL 
115 
247.15 (21.63) 
0.15 (0.04) 
1.78 (0.59) 
Female LW 
115 
126.40 (10.10) 
0.16 (0.04) 
1.73 (0.59) 
Male SL 
112 
177.80 (20.01) 
0.20 (0.08) 
1.63 (0.88) 
Male LW 
112 
89.11 (8.79) 
0.22 (0.08) 
1.40 (0.95) 
2 years before they reach SM50. In contrast, males en- 
ter the fishery at an age of 7.5 years, a few months af- 
ter they reach SM50. Although the annual growth rate 
was higher for female channeled whelk than for male 
whelk, females took longer to reach SM50. Male waved 
This article describes the 
first published study on 
reproductive maturity and 
growth in channeled whelk, 
and it provides the first 
estimates of size at matu- 
rity for this species. Males 
reached SM50 2 years before 
females did. In addition, on 
the basis of SL, male SM50 
was 40 mm less than fe- 
male SM50. Male channeled 
whelk reached SM50 at 66.0 
mm SW (SE 2.9), which is 
below the minimum legal 
size limit in Massachu- 
setts. However, females 
reached SM50 at 89.7 mm 
SW (SE 2.9), 20 mm great- 
er than the minimum size 
limit. This result indicates 
that males have a greater 
chance of copulation before 
they are harvested than do 
females, many of which are 
captured before they reach 
sexual maturity. Females 
enter the fishery at an age 
of 6.3 years, approximately 
D 
Age (years) 
Figure 4 
Results from the von Bertalanffy (VB) growth model used in our study of channeled 
whelk (Busycotypus canaliculatus ) collected in Buzzards Bay, Massachusetts, in Au- 
gust 2010 and July 2011; (A) VB growth model of females (n=115); (B) VB growth 
model of males (n = 112); (C) a comparison of male and female VB growth models; and 
(D) the calculated growth per year for males and females from the VB growth model. 
